Effect of Major Cations and pH on the Acute Toxicity of Cadmium to the Earthworm Eisenia fetida: Implications for the Biotic Ligand Model Approach
2008
Li, Lian-Zhen | Zhou, Dong-Mei | Luo, Xiao-San | Wang, Peng | Wang, Quan-Ying
The purpose of this study was to characterize the individual effect of different cations (Ca²⁺, Mg²⁺, Na⁺, K⁺, and H⁺) on the acute toxicity of Cd to the earthworm Eisenia fetida. Higher activities of the considered cations increased the 48-h LC₅₀ (expressed as Cd²⁺ activities) linearly to different extents in simulated soil solution. The conditional constants for the binding of H⁺ (log K = 5.41), Cd²⁺ (log K = 4.0), Ca²⁺ (log K = 3.35), Mg²⁺ (log K = 2.82), Na⁺ (log K = 1.57), and K⁺ (log K = 2.31) to the biotic ligand (BL) of E. fetida were derived from the toxicity data based on the biotic ligand model (BLM). Furthermore, it was calculated that on average 72% of the BL sites needed to be occupied by Cd²⁺ to induce 50% lethal effect. Autovalidation of the model with the results of the test sets showed that 48-h LC₅₀ could be predicted within a factor of two.
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